There may be public apprehension about where science and technology (S&T) are taking us, but few would want to return to life in 1900. Even in sub-Saharan Africa, despite deepening poverty, a recent increase in civil conflicts across the region and an upturn in endemic diseases including malaria, tuberculosis and AIDS, several development indicators reflect the positive impact of S&T in recent decades:

Average life expectancy increased from 39.9 years to 49.9 years between 1960 and 1994; The infant mortality rate dropped by over 40% in the same period, falling from 166 per thousand live births to 97 per thousand; The percentage of the population with access to safe water has almost doubled in the past two decades, rising from 24% in the period 1975-80 to 42% in the period 1990-96; Real GNP per capita has grown from US$990 in 1960 to US$1377 in 1994. This is above the average growth for least developed countries.

In the past 30 years, the rise of the microcomputer has enabled spectacular progress in many aspects of society, with computing power now almost doubling every 18 months. Cellular phones and cheap computers are beginning to bring Internet to even rural areas of developing countries, with major implications for distance learning and democratisation. Alongside the microchip, the emergence of genetic engineering and biotechnology must be the most revolutionary development in the second half of the last century. And in its wake come a series of possibilities that link science and ethics more than ever before.

1900 Max Planck discovers quanta - the basis of quantum theory
1901 Guglielmo Marconi in Newfoundland receives the first telegraph signal, sent from Cornwall in Great Britain
1903 The Wright brothers successfully demonstrate motor powered flight
1905 Albert Einstein publishes the Special Theory of Relativity
1909 Paul Ehrlich finds a cure for syphilis
1913 Niels Bohr and Ernest Rutherford discover the structure of the atom
1913 Henry Ford invents the moving assembly line for mass production of automobiles
1920 First radio broadcast
1920's Household appliances appear - the vacuum cleaner, electric shaver, spin dryer, electric refrigerator, frozen foods, speaker radio
1922 Frederick Banting and Charles Best discover insulin
1923 Vladimir Zworykin invents the television camera
1924 Edwin Hubble discovers the first new galaxy besides our own
1926 John Logie Baird makes first television broadcast over radio waves
1927 Georges Lemaitre puts forward Big Bang theory of the origin of the universe
1928 Alexander Fleming discovers penicillin
1929 Edwin Hubble puts forward the theory of the expanding universe
1930 The British Broadcasting Corporation starts TV broadcasts
1931 Ernest Lawrence invents the cyclotron to study the behaviour of accelerated atomic particles
1932 James Chadwick describes the nucleus of the atom as composed of protons and neutrons
1935 Invention of nylon and plastics - the first nylon stockings
1942 Enrico Fermi demonstrates the first controlled nuclear reaction
1945 The first atomic bomb is detonated in New Mexico. Atomic bombs were dropped on Hiroshima and Nagasaki in Japan a month later.
1945 The first electronic computer - The Electronic Numerical Integrator Analyzer and Computer (ENIAC) - is demonstrated. It used so much power it caused lights to dim
1947 William Shockley invents the transistor
1948 Percy Julian develops synthetic cortisone
1950 Gertrude Elion develops chemotherapy to treat leukaemia
1952 Jonas Salk produces a vaccine against poliomyelitis
1952 Henri Laborit's discovery of chlorpromazine founds the basis for drug therapies to treat mental illness
1953 James Watson and Francis Crick, with the contribution of Rosalind Franklin and others, discover the double helix structure of DNA, the building block of life
1954 First successful kidney transplant
1957 The Soviet Union launches the Sputnik satellite
1960 Peter Medawar discovers basis of immuno-suppression
1960 Stephen Hawking publishes his Grand Unified Theory of the origin of the universe
1960s Discovery of restriction enzymes - the 'scissors' used to splice genes in genetic engineering
1961 The Soviet Union puts the first astronaut into orbit around the Earth
1964 Murray Gell-Man predicts the existence of quarks
1967 Christiaan Barnard carries out first human heart transplant
1967 Jocelyn Bell identifies pulsars (neutron stars)
1969 Dorothy Hodgkin describes the molecular structure of insulin
1969 US Apollo astronauts walk on the moon
1970's Computerised tomography (CT scan) to look at soft tissues
1970s Some US university campuses linked by a computer network, ARPAnet
1971 Gilbert Hyatt and Intel make the first commercial computer microprocessor
1975 Discovery of endorphins - natural pain killers in the brain
1975 Cesar Milstein and co-workers develop monoclonal antibodies, the 'magic bullets' that can seek out specific antigens and therefore disease-causing organisms
1980s Discovery of prions - a new class of infectious agents unlike viruses. A prion causes Bovine Spongiform Encephaly or 'mad cow disease'
1983 Luc Montagnier and Robert Gallo isolate HIV, the virus that causes AIDS
1987 Discovery of fluoxetine (Prozac) as a therapy for depression
1990 Tim Berners-Lee, a consultant at CERN, the European laboratory for particle physics, along with his colleague Robert Cailliau author software that gave birth of the World Wide Web
1990 Hubble space telescope launched
1996 'Dolly' the sheep is born in Scotland. She was produced by cloning a single mammary cell
1997 Scientists accurately predict the El Niño climatic phenomenon in the tropical Pacific, greatly reducing the social and economic effects of the floods and droughts that follow in many parts of the world.